1. Field of the Invention
The invention relates to digital imaging and, more specifically, to interpolating a color image using multiple gradients.
2. Background Information
In digital color imaging, an image plane having a rectangular array of sensor elements is typically used to measure varying intensities of electromagnetic radiation, such as visible light. For color imaging, it is desirable to capture image data in three color planes, typically red, green and blue (RGB). When the three color planes are combined, it is possible to create high-quality color images. Capturing three color planes is typically accomplished by placing a color filter array (CFA) between the lens and the sensors of the array. For each sensor of the array, the CFA filters all but one of the color planes. Thus, each sensor measures one of red, green, or blue intensity.
One of the most common CFA arrangements or patterns is described in U.S. Pat. No. 3,971,065 to Bayer, and is known as a Bayer array or pattern. The Bayer array is a four-by-four, repeating pattern of color filters as shown below.
G R G R
B G B G
G R G R
B G B G
Several methods have been developed for interpolating the “missing” color elements for each sensor, e.g., the red and blue values at a “green” element, the blue and green values at a “red” element, etc. These methods, however, are either too expensive computationally or produce undesirable artifacts in the resulting image. Thus, a need exists for a method for accurately and efficiently generating missing color values in a digital image sensing system.